Polycyclic aromatic hydrocarbon (PAH) samples in particles were collected with a PM₁₀ sampler in rural areas of Beijing. PAH samples collected on quartz fiber filters were first extracted using dichloromethane with ultrasonic methods, and then were fractionated on an alumina-silica column. Finally, the aromatic and n-alkane fractions were analyzed by gas chromatography with mass spectrometry and gas chromatography-combustion-isotope ratio mass spectrometry. The level of PAHs showed distinctly seasonal changes throughout the year, with the highest concentrations in January and lowest concentration in July. Ʃ16PAH concentrations ranged from 153.23 to 867.41 ng・m⁻³ in January, from 21.53 to 527.42 ng・m⁻³ in April, from 1.84 to 32.02 ng・m⁻³ in July, and from 14.86 to 114.81 ng・m⁻³ in November. Potential PAH emission sources were identified using normal alkane distribution analysis, positive matrix factorization, and compound-specific stable carbon isotope analysis. The results revealed that vehicular emission was the major contributor, and it explained about 48.41% PAH source contribution. The petroleum source explaining 38.63% of the total PAHs was another major PAH source contributor. Coal combustion also was a major PAH contributor, totalling 30.45% of the contribution of PAHs in winter.
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